Conventionally, a dial recliner has a holder and a sector gear which have inner teeth and outer teeth with different teeth numbers therebetween.
Generally, it is common in the principal aspect that the sector gear rotates on its own axis as well as it revolves in the holder in a state that the sector gear intermeshes with the inner teeth of the holder, so that the seatback which is integrally coupled to the sector gear can rotate.
However, a conventional dial recliner has a complicated structure and a lot of parts and components are required to make a manufacturing process complicated.
Especially, according to the conventional dial recliner, the seatback becomes turned back gradually as it is released little by little from its fixed position due to a repeated pressure or impact on the seatback.
It has been widely known that cause of such a problem is a drifting movement, which is called chattering, of a clutch shoe (refer to FIG. 1) among the components constituting the dial recliner that is interposed between the holder and the sector gear.